Field of the Invention
The present invention relates to a display device and a control method thereof.
Description of the Related Art
A problem of a transmission type liquid crystal display device, of which liquid crystal panel is constituted by one panel, is a decrease in contrast caused by leakage of the backlight. One technique to improve the contrast is to insert a second liquid crystal panel (hereafter called “secondary liquid crystal panel”) between a conventional first liquid crystal panel (hereafter called “primary liquid crystal panel”) and a backlight. Thereby contrast can be improved because a gradation number equal to the product of the display gradation numbers of the two liquid crystal panels can be expressed (Japanese Patent Application Laid-Open No. H5-88197).
Another technique to improve the contrast is dividing a screen into a plurality of areas, and controlling the brightness of the backlight and transmittance of the liquid crystal panel for each divided area based on a feature value of the image data of each divided area. Thereby black floats can be suppressed and contrast can be improved (Japanese Patent Application Laid-Open No. 2002-99250).